The common theme of the work is the assessment of differentiation of properties among different excitable tissues in different animals, in different stages of development and different genetic mutants of the same animal. The following specific projects are proposed. 1) ANALYSIS OF CA-DEPENDENT ACTION POTENTIAL. The ion selectivity and kinetics of the Ca channel will be analyzed by voltage clamp technique and compared with those of the Na channels. Muscle cells of a fruit fly ad an Ascaris are considered as materials. Work to be extended to various genetic mutants 2) CA-DEPENDENT ACTION POTENTIAL AND SECRETION. The Ca action potential couples with various effector functions such as the secretory function. Some secretory cells produce Ca dependent action. The role of Ca and the mechanism by which the Ca influx couples the secretion will be analyzed in relation to the Ca action potential. The exocytotic release from the secretory vesicle is monitoed by a change in the membrane capacity. 3) ELECTROPHYSIOLOGY AND THE ROLE OF CA IN EARLY DEVELOPMENT. The membrane potential of the egg cell controls the sperm entry. The formation of the fertilization membrane requires Ca ions. The early development and the coupling between the Ca action potential and the effector function share a number of common mechanisms. 4) ELIMINATION AND CREATION OF NA AND CA CHANNELS DURING DEVELOPMENT. The egg cell membrane often has Ca and/or Na channels. They are either eliminated or created during the process of maturation. The denervation or the application of uncouplers of oxydative phosphorylation creates Na or Ca channels in some adult tissues. The mechanism underlying these processes will be analyzed. 5) THE GATING MECHANISM OF THE MEMBRANE CHANNEL DURING THE ANOMALOUS RECTIFICATION will be studied in immature starfish egg ell membrane both experimentally and theoretically.